Concurrence of Two Rare Conditions: Simultaneous Bilateral Spontaneous Pneumothorax and Congenital Pulmonary Airway Malformation

Abstract

Simultaneous bilateral spontaneous pneumothorax (SBSP) is a very rare type of pneumothorax. Most reported cases are associated with underlying lung diseases. In a small number of pediatric studies, SBSP was found to be associated with human bocavirus bronchiolitis, Langerhans cell histiocytosis, and Mycoplasma pneumoniae infection. The present work examines an interesting case of type 2 congenital pulmonary airway malformation presenting with SBSP and bilateral multiple parenchymal cysts.

Introduction

Congenital pulmonary airway malformation (CPAM), formerly known as cystic adenomatoid malformation (CCAM), is a hamartomatous lung lesion characterized by the proliferation of terminal bronchioles and the development of abnormal alveoli. This malformation was first classified by Stocker et al in 1977 who categorized it into three types according to the size of the cyst. ¹ Currently, CPAM is classified into five main types based on the embryologic level of origin and the cyst's histologic features. ²

Spontaneous pneumothorax (SP) is a type of pneumothorax (PTX) that occurs spontaneously in the absence of iatrogenic or traumatic factors. Simultaneous bilateral spontaneous pneumothorax (SBSP) is a very rare type of SP, accounting for only 1% of all SP cases. ³ In a small number of pediatric studies, SBSP was found to be associated with a few underlying lung diseases such as Langerhans cell histiocytosis (LCH). ⁴ The present study first reported the concurrence of these rare conditions, as a patient presenting a SBSP was diagnosed with of type 2 CPAM based on the typical radiological findings.

Case

A previously healthy 4-year-old male patient was admitted to the emergency department due to the sudden onset of respiratory distress. The patient had tachycardia (150/min), tachypnea (40/min), and intercostal retractions. His breath sounds were diminished and hyperresonance was detected with percussion, bilaterally. The initial chest X-ray showed bilateral PTX ( Fig. 1A ). Laboratory tests detected leukocytosis (24.5 × 10 ³ /uL), an increase in acute phase reactants (procalcitonin 0.23 ng/mL), and respiratory acidosis (pH: 7.29 and pCO ₂  = 50 mm Hg). The patient was admitted to the pediatric intensive care unit (PICU). After admission to the PICU, high-flow oxygen support and empirical antibiotic treatment (ceftriaxone and vancomycin) were initiated. The patient was then treated using bilateral chest tube insertion (size: 16 Fr). The patient's respiratory distress declined and an X-ray showed the successful re-expansion of both lungs ( Fig. 1B ). A chest computerized tomography (CT) scan was performed to detect any underlying disease. The CT scan revealed multiple parenchymal cysts (measuring 0.5–2 cm) in both lung parenchyma ( Figs. 2 and 3 ). Alveolar macrophage (84%), lymphocyte (9%), and neutrophil (4%) were detected in the bronchoalveolar lavage specimen (BAL). Pulmonary Langerhans cell histiocytosis (PLCH) is radiologically similar to CPAM. But Langerhans cells were not detected in BAL and lesions were not confined to the upper and middle zones. So, the patient was diagnosed with type 2 CPAM with typical clinical and tomographic findings. Type 2 CPAM is frequently associated with other congenital anomalies but other organ anomalies were not found in our case. A consultation was performed in the thoracic surgery clinic and it was determined that surgical intervention was not required. The intercostal drainage tubes were removed on the day 3. The patient was informed about the complications and was discharged on the day 6. He was referred to a pediatric chest disease clinic for long-term follow-up.

Fig. 1.

Chest X-ray showing simultaneous bilateral spontaneous pneumothorax and ( A ) and reexpansion of the lungs following bilateral chest tube insertion ( B ).

Fig. 2.

Chest CT-scan showing multiple parenchymal cysts in both lung parenchyma. CT, computed tomography.

Fig. 3.

The sagittal and frontal reconstruction of CT examination. CT, computed tomography.

Discussion

CPAM is a rare, nonhereditary, developmental abnormality of the lung that represents 25% of congenital lung malformations. Type 2 CPAM, which is characterized by cystic lesions of 0.5 to 2 cm in size originating from the terminal bronchioles, comprises 15 to 30% of all CPAM cases and is the type most likely to occur with other system anomalies. ² In the present case, the patient's CT image was consistent with type 2 CPAM. PLCH, which is radiologically similar to CPAM, is a rare event in childhood. Given the isolated lung involvement, Langerhans cells were not detected in the BAL specimen, and lesions were not confined to the upper and middle zones, so PLCH was not considered for our case based on radiological and clinical findings. The BAL examination is not sufficient to exclusion PLCH. In our patient, PLCH was excluded with the help of clinical and radiological features, not only with BAL examination.

Although radiological examinations are useful in diagnosis, histological examinations are very useful in typing and differential diagnosis. Histologically, cartilage is absent or there are small cartilage foci in the wall of the bronchial structures, patients with CPAM present with small bronchial communications which are very likely responsible for the infections and hyperinflation. ⁵ Cystic formations are covered with columnar or cuboidal epithelium. Since lung biopsy was not recommended by thoracic surgery clinic, histological examination could not be performed in our patient. This is an important limitation of our study.

In symptomatic cases, CPAM can be treated using surgical procedures, such as a lobectomy. The long-term outcomes of such procedures are generally very good, with the majority of children leading healthy and active lives after treatment. However, surgical intervention can be postponed if the patient is asymptomatic and the cyst is resolving. Because the patient in the present case had bilateral multiple cysts and was clinically stable, surgical intervention was postponed. It has been reported that tube thoracostomies can be used to effectively stop air leakage within 5 hours in 52% of patients and within 48 hours in 82% of patients. ^{6 7} In cases of prolonged air leakage lasting more than 15 days, surgical intervention should be considered. ⁸ A bilateral tube thoracostomy was performed on the patient in the present case; no persistent air leaks were demonstrated after 60 hours.

Some patients with CPAM are asymptomatic before or at birth. After the neonatal period, becoming symptomatic varies from 3 to 86% in reported series. ⁹ Symptoms included pneumonia, respiratory distress, pneumothorax, and chronic cough. Our patient presented with SBSP at the age of 4 years. Infection, recurrent pneumothorax, and malignancy may occur in patients who untreated or underwent lobar segmental resection. ^{9 10} Laberge et al reported that 12 patients were diagnosed postnatally and one patient presented with recurrent pneumothorax. ¹¹ The patient was informed about the complications. No complication developed during the 12-month follow-up period.

Conclusion

SBSP should be considered in patients with sudden onset respiratory distress. Advanced imaging modalities, such as CT scans, should be performed as SBSP frequently occurs as a result of an underlying lung disease. In such cases, CPAM should be considered in the differential diagnosis.